Metal electroplating process and bath



\ United States Patent 3,276,977 METAL ELECTROPLATING PROCESS AND BATH Wolf-Dieter Willmund and Wennemar Strauss, Dusseldorf-Holthausen, and Alfred Kirstahler, Dusseldorf, Germany, assignors to Dehydag Deutsche Hvdrierwerke G.m.b.H., Dusseldorf, Germany, a corporation of Germany No Drawing. Filed Feb. 11. 1963, Ser. No. 257,735 Claims priority, application Germany, Feb. 13, 1962,

' D 38,134: Feb. 14, 1962, D 38,147

34 Claims. (Cl. 204-44) This invention relates to a process and bath for the elect-rodeposition of metals and to additives for such process and bath.

We have found that metal electroplating baths which produce high quality metal electrod'eposits are obtained by adding to the customary electroplating baths substitution products of acid sulfur-containing phosphorus derivatives which comprise organic radicals attached to the molecule through an oxygen, sulfur, nitrogen or phosphorus atom.

The compounds in question are those which, for example, are derived from thionophosphoric acid, thiolothionophosphoric acid, dithiolothionophosphoric acid, tetrathiophosphoric acid, thionophosphonic acid, thiolothionophosphonic acid, trithiophosphonic acid, thiophosphinic acids such as thionophosphinic acid in dithiophosphinic acid, or esters thioesters or amides of these or similar acids, and correspond to the general formula In this general formula R, R and R" stand for aliphatic, cycloaliphatic, aromatic and a-raliphatic radicals which may also be substituted or interrupted by heteroatoms or heteroatom groups, X, Y and Z stand for heteroatoms and heteroatom groups, such as O, S, NH, and the like, and L represents a water-solubilizing inorganic or organic group. The symbol 1: represents an integer from 0 to 1. Thus X and/ or Y and/ or Z as well as R" may be omitted. Suitable water-solubilizing groups are anionic, cationic and electroneutral groups, such as COOH, SO H, PO H, SO H, PO H PO H water-solubilizing organic basic radicals, such as primary, secondary or tertiary amino groups Which have been neutralized with acids, quaternary ammonium groups, polyalkyleneglycol radicals, sugar radicals, also metals, hydrogen, and the like.

The products which are employed in accordance with the present invention are known compounds or may be produced pursuant to known processes, such as those described in German published applications 1,101,417 and 1,014,989, in US. Patent 2,391,184, and in Chemical Abstracts 40, col. 7039 (1946), 41, col. 2012-2014 (1947) and 47 col. 9909 (1953), German Patent 938,548, US. Patent 2,959,608, French Patent 1,234,879, Swedish Patent 5736-58 2, and in the Journal of Applied Chemistry (USSR) 25 (87), 2274-2277 (November 1955) (abstracted in Centralblatt (1957), p. 84).

It is, therefore, an object of this invention to provide an electroplating bath and process for obtaining bright and level el'ectrodeposits of metals.

Another object is to provide novel additives for electroplating baths which give a brightening and a leveling effect.

These and other objects of my invention will become apparent as the description thereof proceeds.

The following are a few examples of substitution products of acid sulfur containing phosphorus derivatives which may be used in accordance with the invention in customary electroplating baths.

"ice

(1) Sodium salt of 0,0-diphenylthionophosphoric acid 0 ONa (2) Ammonium salt of 0,0-dioctyl-thiolothionophosphoric acid C H1r-0 s s n- \S-NH4 (3) 0,0,-dioctadecyl-thiolothionophosphoric acid mHar-O S (4) Sodium salt of 0,0-diisopropyl-thiolothionophosphoric acid CH3 (5) 0,0-diphenyl-thiolothionophosphoric acid (6) Ammonium salt of dibenzyl-tetrathiophosphoiic acid (7) 0,0-diphenylthionophosphoric acid amide O\P/S 0 S Na S NH,

(8) Ammonium salt of fi-naphthyl-O-ethylester-thiolot-hionophosphonic acid C2H5O/ sNH,

(9) 2 cyclohexenyl O ethyl'ester thiolothionophosphonic acid 3 (12) Diphenyl-dithiophosphinic acid sodium (13) Sodium salt of 0,0-diethyl-thiolothionophosphoric acid-w-sulfopropylester CzHO\ %S CgH5O S CHg-CHa-CHz- S O Na (14) Ammonium salt of 0,0-didodccyl-thiolothionophosphoric acid-w-sulfopropylester (15) Ammonium salt of 0,0-dioctadecyl-thiolothionophosphoric acid-w-sulfopropylester (l7 Sodium salt of 0,0-diphenyl-thiolothionophosphoric acid-w-sulfopropylester (18) Sodium salt of 0,0-di-p-chlorophenyl-thiolothionophosphoric acid-w-sulfopropylester (19) Ammonium salt of S,S-dibenzyl-tetrathiophosphoric acid-propylester-w-sulfonic acid (20) w-Sodiumsulfopropyl-thionophosphoric acid dianilid (21) 0,0-dipheny1-thiolothionophosphoric acid-S-n-(2- hydroxy) proylesterpyridinium chloride V 4 (22) Sodium salt of 0,0 -dipheny1- thiolothionophosphoric acid-w-carboxyethylester (23) Sodium salt of O-phenyl-Gethylester-thiolothionophosphoric acid-propylester-w-sulfonic acid (24) 0,0-diphenyl-thiolothionophosphoric acid-S-benzylester-o-sulfonic acid sodium O Na (25) Disodium 0,0, di-p-tolyl-thiolothionophosphoric acid-S-methylesterphosphate (26) 0,0-diisopropyl thiolothionophosphoric acid -S- penta-ethylencglycolester CHO CH-O

(27) 0,0-diphcnyl-thionophosphoric acid-w-aminoethylester-hydrochloride (28) Ammonium salt of ,B-naphthyl-O-ethylester-thiolothionophosphonic acid-S-propylester-w-sulfonic acid s 021150 S-CH1CHzCHzSO N'H4 (29) Sodium salt of 2- cyclohexenyl-O-ethylester-thiolothiono-phosphonic acid-S-propylester-w-sulfonic acid (30) 0,0-diethyl-thionophosphonic acid propylester-wsulfonic acid sodium CzHxr-O S C2H5O CHICHiCHTSOaNQ (31) Sodium salt of diphenyl-dithiophosphinic acid propylester-w-sulfonic acid (32) Diphenyl-dithiophosphinic acid-ethylester-pyridinium-bromide In contrast to the additives heretofore customarily used, the additives according to the present invention may be employed as brightening additives in all types of metal electroplating baths, that is, in acid or cyanide baths of the metals copper, brass, bronze, zinc, cadmium, silver, nickel, etc. It was surprising that the sulfur-containing organic phosphorous derivatives according to the present invention are eifective not only in individual instances in certain definite metal electroplating baths, but that they produce a brightening efiect in practically all of the known metal electroplating baths; this was the more surprising since it was heretofore known of sulfur-free phosphorous compounds, such as organic phosphoric acid esters or phosphonates, that they possess only minor electroplating effects which, under the most favorable circumstances, can be considered as improvements in the fineness of the grain of the electroplate.

Many of the products employed in accordance with the present invention not only possess brightening properties but also strong leveling effects, whereby they have been found to be particularly useful for electro-deposition of metals.

The amounts in which the additives according to the invention are added to the baths lie at about 0.001 to 20 gm. per liter of bath liquid; in general, the baths are operated at temperatures which are customary for the various types of baths and the current densities lie between about 0.25 to 8 amperes per drn. and may sometimes be even higher. The current density range of optimum brightening effect is different for the individual compounds and depends upon the composition of the bath; in many cases, however, it is of considerable breadth. If necessary, the additives may also be employed in conjunction with other known brightening agents as well as with leveling agents, pore preventing agents, agents which tie'up the hardness components, inhibitors, wetting agents, conductive salts, etc. The metal substrates to be electroplated may be all of the types of metals previously employed for this purpose, such as iron, steel, zinc, copper, nickel and other non-precious metals or metal alloys. If necessary, the non-precious metals are, as customary, initially provided with a thin copper base deposit in an alkaline cyanidebath.

Metal electrodeposits are obtained with the additives according to the invention, which very firmly adhere and possess a good brightness effect. Moreover, the additives according to the present invention have the advantage that they are chemically very stable in the various electroplating baths, so that these baths remain operative for long periods of time.

The products according to the present invention may especially be used in the direct copperplating process in which firmly adhering copper electrodeposits are deposited on non-precious metals, such as iron, without preliminary cyanide copperplating, that is, by pretreating the metal objects to be copperplated in an acid pickling bath comprising pickling agents having a high inhibiting effect and subsequently electroplating in an acid copper bath without an intermediate rinsing step.

To the extent that the products according to the present invention are sparsely soluble, they may also be used with advantage as a bottom additive in self-regulating electroplating baths, where they are advantageously provided in a solution filter which is inserted into the circulation system after the customary contamination trap filter. Because of the elfect of the wetting agents which are customarily used in such baths, these baths may be operated over a very wide range of concentration and, because of the self-regulation of the brightening agent from the insoluble bottom substance, may be practically considered as requiring no surveillance at all.

The following examples are set forth to further illustrate the invention and to enable persons skilled in the art to better understand and practice the invention, and are not intended to be limitative.

Example I 0,0-diphenyl-thiolothionophosphoric acid (No. 5) was added as a brightening agent to an acid copper electroplating bath which container per liter 60 gms. of sulfuric acid, 210 gms. of copper sulfate, and 8 gms. of an addition product of 8 mols of ethylene oxide to 1 mol of a coconut fatty alcohol mixture C -C as a wetting agent. When 70 mgm. of this additive was used per liter of bath liquid, semi-bright, firmly adhering, high-leveled copper electrodeposits with good ductility were obtained in a current density range of 0.25 to 8 amperes/dm.

Example 11 0,0-dioctadecylthiolothionophosphoric acid (No. 3) was charged as a sparsely soluble brightening agent into a solution filter located downstream from a customary contamination trap filter in an acid copper electroplating bath of the same composition as in Example I, the bath being provided with a means for recycling the bath fluid. At a recycling rate of one bath volume per hour, the bath furnished satisfactorily bright, smooth, pore-free and firmly adhering copper electrodeposits within a current density range of 0.2 to 8 amperes/dm.

Example 111 The sodium salt of 0,0-diethyldithiophosphinic acid (No. 11) was added as a brightening agent to a cyanide zinc bath which contained per liter 55.5 gm. of zinc cyanide, 71.5 gm. of sodium hydroxide and 40.3 gm. of sodium cyanide. When 2 to 10 gm. of the additive per liter of bath liquid were used, firmly adhering ductile Zinc elec trodeposits having a beautiful uniform brightness were obtained within a current density range of 0.5 to 4 amperes/dmf".

Example V 0.1 to 0.2 gm. of the sodium salt of 0,0-diisopropylthiolothiono-phosphoric acid (No. 4) were added as a brightening agent per liter of bath fluid to a cyanide brass electroplating bath containing per liter 21 gm. of copper- (I)-cyanide, 53.8 gm. of zinc cyanide, gm. of sodium cyanide and 20 gm. of anhydrous sodium carbonate. At a bath temperature of 30 C. in a current density range of 0.25 to 2.5 amperes/d m. this electroplating bath pro duced a uniform, spot-free, yellow brass electrodeposit.

Example V1 9.5 of :diphenyl-dithiophosphinic (acid sodium (No. 12) was added as a brightening agent per liter of bath liquid to a cyanide copper bath composed of 105 gm./ liter of copper-(I)-cyanide, 128 gm./1iter of sodium cyanide and 30 gum/liter of sodium hydroxide. bath temperature of 70-80 C. this bath produced full bright, firmly adhering and lductile copper electrodeposits in a high current density range of 3-5 amperes/ dill- Example VII When sheet steel was electroplated at increasing temperature and at a current density of 4-9 amperes/dirn. in an acid zinc bath containing per liter 200 gm. of zinc sulfate, 1 gm. of glacial acetic acid, and as a brightening agent 1 gm. of ammonium salt of dibenzyl-tetrathiophosphoric acid (No. 6), satisfactorily bright and firmly adhering zinc electrodeposits were obtained.

Example VIII When 0.5 to 3 gm./liter of the ammonium salt of fl-naphthyl O ethylester-thiolothionophosphonic acid (N0. 8) were used as a brightening agent in a cyanide cadmium bath composed of 30 gm./liter of cadmium oxide and 110 gm./liter of sodium cyanide, electroplating at room temperature in a current density range of 0.5 to arnperes/dm. produced ifiull bright electrodeposits which did not require any further subsequent treatment,v

even without the presence of nickel ions.

Example IX Example X 0.1 to 0.3 gm. of 2-cycl0hexenyl-Oethyl-ester-thiolothionophosphonic acid (No. 9) was added (as a brightening agent per liter of bath liquid to a copper-cadmiumbronze bath which contained per liter 23 gm. of copper- (I)-cyanide, 1.2 gm. of cadmium oxide, 34 gm. of sodium cyanide and gm. of sodium carbonate. At a bath temperature of -35" C. this bath'produced uni- At a form, firmly adhering, satisfactorily bright, bronzecolored electrodeposits in a current density range of 0.1 to 1.5 aimperes/dnL Example XI When 0.1 gm./liter of 0,0-diphenylthionophosphoric acid amide (No. 7) was added as a brightening agent to a nickel bath having the composition described in Example IX, satisfactorily bright, finmly adhering and ductile nickel electrodeposits were obtained at a bath temliquid.

Example XII 1-10 mgm. of 0,0-diethylthionophosphonic acid (No.

10) were added per liter of bath liquid -to an acid copper bath having the same basic composition as that in Example I. This bath produced finmly adhering, bright copper electrodeposits with a very fine grain in a current density range of 1-6 amperes/dmF.

8 Example XIII The ammonium salt of 0,0didodecylthiolothionophosphoric 'acid-w-sulfopropylester (No. 14) was added as a brightening agent to an acid copper bath which contained per liter 60 grams of sulfuric acid, 210 gm. of copper sulfate and 8 gm. of an addition product of 8 mols of ethylene oxide to 1 mol of a coconut fatty alcohol' mixture of C -C as a wetting agent. The ammonium salt was obtainedby dissolving 48.3 gm. of ammonium 0,0-didodecylthiolothionophosphate (produced analogous to the examples of U.S.I=atent 2,063,- 629) in 250 cc. of ethanol and adding 12.2 gm. of propane sultone to the solution dropwise at 65 f C. Thereafter, the reaction mixture was stirred for 3 hours and was then evaporated in vacuo. 60.3 gm. of a substance was obtained whichwas soluble in ether and petroleum ether and whose analysis corresponds to the compound of the above nomenclature and structure.

When 30 to 200 mgm./ 1. of bath fluid of this compound were added, full bright, firmly adhering copper deposits were obtained in a current density range of 0.25 to 8 amperes/idm. which did not require any finishing treatment and rinsing.

ExampleXI V 0.5 gm. of 0,0-dicyclo-hexyl-thiolothionophosphoric acid S propylester w pentaglycolether (No. 1 6) were added per liter of bath fluid to an acid copper bath consisting of 210-g1m./l. of copper sulfate and 60 gm./l. of sulfuric acid. Full bright, smoother, pore-free and firmly adhering copper electroplates were obtained in a current density range of 0.5 to 8 amperes/ dmf even without the addition of a wetting agent.

Example XV The sodium salt of 0,0-diphenyl-thiolothionophosphoric acid-w-sulfopropylester (No. 17) was added as a brightening agent to an acid copper electroplating bath having the basic composition indicated in Example XIH. This salt was obtained when 28.2 gm. of 0,0-diphenylthiolothionophosphoric acid were dissolved in 200 cc. of water having 4 gm. of sodium hydroxide dissolved therein, heating the solution to a temperature between 60-65 C., thereupon adding 122 gm. of molten propane-sultone dropwise over a period of 4 minutes and stirring the reaction mixture at the same temperature for 2 hours. After reaction with ether, evaporation of the aqueous solution in vacuo, and recrystallization of the residue from benzene, 24.3 gm. of the crystallized propylestersulfonate C H NaO PS of a molecular weight of 426 were obtained. The analysis showed for carbon: calculated 42.92%, found 41.15%; for hydrogen: calculated 3.76%, found 4.85%; and for sulfur: calculated 22.52%, found 22.02%.

When 10-30 mgmjl. of bath liquid of this compound were added, full bright, firmly adhening, satisfiactori'ly leveled copper electroplates were obtained with a current density range of 0.25 to 8 amperes/dmfi.

Example XVI thiolothionophosphoric acid ammonium (prepared analogous to the method of L. Cambi, Chimica e Ind. 26, 97 (1944) from p-chlorophenol and P 8 in xylene at reflux temperature) were dissolved in 250 cc. of ethanol and 20 cc. of water, and 12.2 gm. of propane sultone were added to the solution at 65-70 C. within a period of five minutes. Thereafter, the reaction mixture was stirred at the same temperature for 3 hours and was filtered. After allowing the mixture to stand at C. for two days, 5.5

molecular weight 490, the following values: Cl found 14.60%, calculated 14.48%. Sulfur found 19,22%, calculated 19.58%.

When 5 to 50 mgm. of this compound were added per liter of bath liquid, copper electroplates with a uniform full brightness and simultaneous satisfactory leveling effect were obtained within a current density range of 0.5 to 8 amperes/dm. at a bath temperature of about C.

Example XVII When sheet steel was electroplated at increasing temperatures and at a current density of 4 to 9 amperes/dm. with the aid of an acid zinc bath containing per liter-200 gm. of zinc sulfate, 1 gm. of glacial acetic acid, and as a brightening agent 1 gm. of the ammonium salt of S,S- dibenzyl tetrathiophosphoric acid-propylester-w-sulfonic acid (No. 19) full bright, firmly adhering zinc electrodeposits were obtained which did not require any subsequent pickling treatment.

Example XVIII An acid copper bath of the same basic composition as that described in Example XIII was modified with wsodium sulfopropylthionophosphoric acid dianilid (No. 20) as a brightening agent in an amount of 5 to 90 mgm./l. of bath fluid. Full bright, firmly adhering and satisfactorily leveled copper electrodeposits were obtained within a current density range of 0.25 to 8 amperes/dm.

Example XIX When an acid copper electroplating bath having the same composition as that in Example XIII was modified with 1 to 5 mgm./l. of bath liquid of the ammonium salt of B-naphthyl-O-ethylester-thiolothionophosphonic acid- S-propylester-w-sulfonic acid (No. 28) as a brightening agent, full bright, firmly adhering and distinctly leveled copper electrodeposits were obtained within a current density range of 0.5 to 6 amperes/dmF. The leveling effect was still further improved by the addition of l to 2 mgm./l. of bath fluid of the sodium salt of N-phenyl-N- carboxymethylthiourea.

The same result was obtained when the sodium salt of 2 cyclohexenyl-O-ethylester-thiolothionophosphonic acid-S-propylester-w-sulfonic acid (No. 29) was added as a brightening agent in the same quantity.

Example XX 0.05 gm. of diphenyl-dithiophospinic acid ethylesterpyridinium bromide (No. 32) was added per liter of bath fluid to a nickel bath composed of 265 gm./l. of nickel sulfate, 53 gm./l. of nickel chloride and 33 gm./l. of boric acid, comprising as an additional brightening agent 2 gm./l. of benzylbenzoylamide. The bath produced full bright, firmly adhering ductile and satisfactorily level nickel electroplates at a bath temperature of 55 C. in a current density range of 0.5 to 6 amperes/dm. The same effect was obtained when the same amount of 0,0-diphenylthiolothiono-phosphoric acid-S-n-(Z hydroxy)-propylester-pyridiniumchloride (No. 21) was added to the bath. When 0,0-diphenyl-thionophosphoric acid-w-aminoethylester hydrochloride (No. 27) was added per liter of bath fluid in place of the above indicated additives No. 32 and 21, full bright nickel electroplates with good adhering properties, but somewhat lesser leveling efiects, were obtained.

Example XXI When 1 gm./l. of sodium salt of 0,0-diphenyl-thiolothionophosphoric acid-w-carboxyethylester (No. 22) was added as a brightening agent to a cyanide cadmium bath composed of 30 gm./l. of cadmium oxide, gm./l. of sodium cyanide, 1 gm./l. of potassium and 1.5 g./l. of a sulfated fatty alcohol polyglycol ether, full brightness was achieved within a current density range of 0.5 to 4 amperes/dm. A subsequent pickling in a Weak oxidizing medium was not necessary.

Example XXII When 1 to 5 mgm. of sodium 0,0-diphenyl-thiolothionophosphoric acid-S-benzylester-O-sulfonic acid (N o. 24) were added as a brightening agent per liter of bath fluid to an acid copper bath of the same composition as that descirbed in Example XIII, full bright, smooth and firmly adhering copper electrodeposits of good ductility were obtained in a current density range of 0.25 to 8 amperes/ dm.

Example XXIII 1 gm. of disodium 0,0 di-p-tolyl-thiolothionophosphoric acid-S-methylesterphosphate (No. 25) was added as a brightening agent per liter of bath liquid to a cyanide copper electroplating bath composed of 81.7 gm./l. of copper (I) cyanide, 118.3 gm./l. of potassium cyanide, 10 gm./l. of Rochelle salt, 15 gm./l. of sodium cyanide, 20 gm./l. of sodium hydroxide and 55 gin/l. of sodium carbonate. This bath produced satisfactorily bright, very fine-grained and firmly adhering copper electrodeposits at a bath temperature of 75-80 C. over the entire current density range of 0.5 to 8 amperes per dm.

Example XXIV 0.2 gm. of 0,0 diisopropyl-thiolothiono-phosphoric acids-pentaethyleneglycolester (No. 26) was added as a brightening agent per liter of bath liquid to a cyanide brass electroplating bath composed of 21 gm./l. of copper (I) cyanide, 53.8 grn./l. of zinc cyanide, 75 gm./l. of sodium cyanide and 20 gm./l. of anhydrous sodium carbonate. This bath produced a completely uniform, spot-free, satisfactorily bright, yellow brass electroplate at a bath temperature of 30 C. in a current density range of 0.25 to 2.5 amperes per dm.

Example XXV When 10 mgm. of 0,0-diethylthionophosphonic acidpropylester-o-sodium sulfonate (No. 30) were added as a brightening agent per liter of bath liquid to an acid copper electroplating bath having the composition de scribed in Example XIII, full bright, smooth and firmly adhering copper electrodeposits of good ductility were obtained in a current density range of 1 to 6 amperes/dmP.

While we have set forth certain specific embodiments and preferred modes of practice of our invention, it will be understood that the invention is not limited thereby, and that various changes and modifications may be made without departing from the spirit of the disclosure or the scope of the appended claims.

We claim:

1. An electroplating process for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises electrodepositing the metals from a bath comprising an aqueous solution of a compound of the metal to be electrodeposited in the presence of an additive compound having the structural formula:

wherein R and R' represent members selected from the group consisting of aliphatic, cycloaliphatic, aromatic and aralkyl radical and R represents members selected from the group consisting of aliphatic, cycloaliphatic, aromatic and aralkyl which may contain heteroatoms selected from the group consisting of N and O, X, Y and Z represent heteroatoms and heteroatom groups selected from the groups consisting of O, S and NH, and L represents water-solubilizing groups selected from the group consisting of COOH, SO H, -PO H, -SO H, PO H PO H primary, secondary and tertiary amino groups neutralized with an acid, quaternary ammonium groups, polyalkyleneglycol radicals, sugar radicals and metals and n is an integer from to 1, said additive being present insufficient amount to obtain said electrodeposits.

2.An electroplating proces for producing bright and level. electrodeposits of metals capable of being electrodeposited which comprises electrodepositing the'metals from a bath comprising an aqueous solution of a compound of the metal to be electrodeposited in the presence of from about 0.001 to g./l. of an additive compound having the structural formula:

wherein R and R represent members selected from the group consisting of aliphatic, cycloaliphatic, aromatic and aralkyl radicals and R represents members selected from the group consisting of aliphatic, cycloaliphatic, aromatic and aralkyl which may contain heteroatoms selected from the group consisting of N and O, X, Y and Z represent heteroatoms and heteroatom groups selected from the groups consisting of O, S and NH, and Lrepresents water-solubilizing groups selected from the group consisting of wherein R and R represent members selected from the group consisting of aliphatic, cycloaliphatic, aromatic and aralkyl radicals and R represents members selected from the group consisting of aliphatic, cycloaliphatic, aromatic and aralkyl which may contain heteroatoms selected from the group consisting of N and O, X, Y and Z represent heteroatoms and heteroatom groups selected from the groups consisting of O, S and NH, and L represents water-solubilizing groups selected from the group consisting of primary, secondary and tertiary amino groups neutralized with an acid, quaternary ammonium groups, polyalkyleneglycol radicals, sugar radicals and metals and n is an integer from 0 to 1, said additive being present in sufficient amount to obtain said electrodeposits.

5. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and from about 12 0.001 to 20 g./l. of an additive compound having the structural formula:

wherein R and R represent members selected from the group consisting of aliphatic, cycloaliphatic, aromatic and aralkyl radicals and R" represents members selected from the group consisting of aliphatic, cycloaliphatic,aromatic and aralkyl which may contain heteroatoms selected from the group consisting of N and O, X, Y .and Z represent heteroatoms and heteroatom groups selected from, the groups consisting of O, S and NH, and L representswater-solubilizing groups selected from the group consisting of primary, secondary and tertiary amino groups neutralized with an acid, quaternary ammonium groups, polyalkyleneglycol radicals, sugar radicals and metals and n is an integer from 0 to 1.

6. The bath of claim 5, comprising in addition known brightening agents, pore-preventing agents, hardness binders, inhibitors and wetting agents.

7. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an addi tive compound from about 0.001 to 20 g./l. of 0,0-diphenyl-thiolothionophosphoric acid.

8. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of 0,0-dioctadecylthiolothionophosphoric acid.

9. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of ammonium salt of 0,0-dioctylthiolothionophosphoric acid.

10. An electroplating bath for producing bright and level electrodeposits of metals capable, of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of sodium salt of 0,0-diethyldithiophosphinic acid.

11. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an addi tive compound from about 0.001 to 20 g./l. of sodium salt of 0,0-diisopropylthiolothionophosphoric acid.

12. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of diphenyldithiophosphinic acid sodium.

13. An electroplating bath for producing bright and level electrodeposits of metals capable of being'electrodeposited which comprises an aqueous solution of a com- 7 pound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of ammonium salt of dibenzyltetrathiophosphoric acid.

14. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of ammonium salt of B-naphthyl-O-ethylester-thiolothionophosphonic acid.

15. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of sodium salt of 0,0-diphenyl-thionophosphoric acid.

16. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of 2-cyclohexenyl-O-ethylester-thiolothionophosphonic acid.

17. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of 0,0-diphenylthionophosphoric acid amide.

18. An electroplating bath for producing bright and level electrodeposits of metal capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of 0,0-diethylthionophosphonic acid.

19. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of ammonium salt of 0,0-didodecylthiolothionophosphoric acid-wsulfopropylester.

20. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of 0,0-di cyclo-heXyl-thiolothionophosphoric acid-S-propylester-wpentaglycolether.

21. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of sodium salt of 0,0-diphenyl-thiolothionophosphoric acid-w-sulfopropylester.

22. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./1. of sodium salt of 0,0-di-p-chlorophenyl-thiolothionophosphoric acidw-sulfopropylester.

23. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of ammonium salt of S,S-dibenzyltetrathiophosphoric acid-propylester-w-sulfonic acid.

24. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of w-sodium sulfopropylthionophosphoric acid dianilid.

25. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 .to 20 g./l. of ammonium salt of ,6-naphthyl-O-ethylester-thiolothionophosphonic acid-S-propylester-w-sulfonic acid.

26. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./1. of sodium salt of 2-cyclohexenyl-O-ethylester-thiolothionophosphonic acid-S-propylester-w-sulfonic acid.

27. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of diphenyldithiophosphinic acid ethylester-pyridinium bromide.

28. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of 0,0-diphenyl-thiolothionophosphoric acid-S-n-(Z hydroXy)-propylesterpyridiniumchloride.

29. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.01 to 20 g./l. of 0,0-diphenyl-thionophosphoric acid-w-amino-ethylester hydrochloride.

30. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of sodium salt of 0,0-diphenyl-thiolothionophosphoric acid-w-carboxyethylester.

31. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an addiive compound from about 0.001 to 20 g./l. of sodium 0,0-diphenyl-thiolothionophosphoric acid-S-benzylester- O-sulfonic acid.

32. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of disodium- 0,0-di-p-tolylthiolothionophosphoric acid-S-methylesterphosphate.

33. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of 0,0-diisopropyl-thiolothiono-phosphoric acid-S-pentaethyleneglycolester.

34. An electroplating bath for producing bright and level electrodeposits of metals capable of being electrodeposited which comprises an aqueous solution of a compound of the metal to be electrodeposited and as an additive compound from about 0.001 to 20 g./l. of 0,0di-

ethylthionophosphonic acidpropylester-w-sodium sulfonate.

References Cited by the Examiner UNITED STATES PATENTS 2,250,049 7/ 1941 Moyle 260461 2,839,458 6/ 1958 Foulke et a1 204-49 2,875,230 2/1959 Coover et al 260461 3,030,282 4/1962 Passal 20452 3,035,991 5/1962 Strauss et a1 20451 3,037,918 6/1962 Ostrow et al. 204-52 3,047,619 7/1962 Brace 20445 X 3,084,111 4/ 1963 Strauss et al. 204-45 X 3,165,513 1/1965 DAlelio 20445 X JOHN H. MACK, Primary Examiner.

G. KAPLAN, Assistant Examiner. 

1. AN ELECTROPLATING PROCESS FOR PRODUCING BRIGHT AND LEVEL ELECTRODEPOSITS OF METAL CAPABLE OF BEING ELECTRODEPOSITED WHICH COMPRISING ELECTRODEPOSITING THE METALS FROM A BATH COMPRISING AN AQUEOUS SOLUTION OF A COMPOUND OF THE METAL TO BE ELECTRODEPOSITED IN THE PRESENCE OF AN ADDITIVE COMPOUND HAVING THE STRUCTURAL FORMULA: 